Resumo:
The study aimed to define critical rainfall and hydraulic thresholds to support a flood
warning system in Itabuna, Bahia, an urban region with limited hydrological monitoring.
To achieve this, hydrological and hydrodynamic modeling was used to simulate flood
events under different rainfall scenarios. Rainfall data, from a grid, and flow data,
obtained from a fluviometer, applied for model calibration, underwent a prior
consistency analysis. It was found that the grid rainfall was representative for the study
area based on the applied statistical metrics. However, the flow data showed
discontinuity and overestimation, compromising the accuracy for modeling. The
applied hydrological model was satisfactorily calibrated for two flood events in the study
area, with one of the calibrations chosen for the continuation of the study. With the
calibrated hydrological model, ten hydrographs were generated, corresponding to ten
different accumulated rainfall amounts, which were propagated in the hydrodynamic
model, resulting in flood scenarios for the municipality. The methodology enabled the
identification of accumulated rainfall amounts that led to the exceedance of alert levels,
associated with peak flows in different monitored sections. In the most intense event,
all alert thresholds in the areas of interest were exceeded. Maps representing the
extent of floods and wave propagation time demonstrated the evolution and severity of
the events, indicating a significant increase in the affected area in proportion to the
rainfall intensity. Additionally, maps of body instability risk (such as overturning and
slipping) revealed dangerous situations in areas near watercourses from a certain level
of event severity, with the expansion of higher-risk zones. This work highlights the
feasibility of a methodology to analyze and correlate accumulated rainfall with hydraulic
parameters in locations with limited hydrological monitoring capacity. Such an
approach can contribute to the development of flood preparedness and response plans
in municipalities with restricted monitoring infrastructure, offering support to civil
defense agencies in defining alert levels and communicating risks to the population.
